WaterMark to PDF

we have a requirement to Add watermark to PDF before approval of the PDF. Once Its approved water mark should not available.

Is there any scope we can add watermark in HTML ( from left-bottom to right-top ) position we are using headers and footers in existing PDFs ( Multiple Page PDF ) and once it approved we have to remove the watermark from the PDF.

Currently I am thinking of using PDFBox overlay functionality for this purpose, But in this we have to add water mark after PDF created. ( we have changes to PDF's multiple times before approval of the final PDF page.